Is that a set of key,key要不要加s?

Is that a set of key,key要不要加s? 那么a set of key 中“key"一定要加s吗 a set of keys 为什么key加‘s’还有play computer games 也加‘s' a set of ____(key). There is ( ) A.key B.a set of key C a set of keys D.keys 选哪个 改错 I have a set of key. 还有I have a set of (key). she has _ key 中间要不要加a? 是a set of keys还是a set of key? I have two __ .A.set of keys B.set of key C.sets of keys D.s 英语翻译A new set of nsems semaphores is createdif key has the v 适当填空 There is a set of---------(key) on the table